1. Field of the Invention
The present invention relates to image processing method and apparatus for transmitting a video signal, a movement image signal, or the like including a luminance component and a chrominance component.
2. Related Background Art
Hitherto, there has been known a method whereby when processing a video signal in a real-time manner, the processing system is divided into a plurality of phases and processes are executed in parallel in consideration of a processing speed.
On the other hand, generally, a luminance signal has a frequency band wider than that of a chrominance signal. For example, in an A/D converting unit, a sampling rate when converting an analog signal into a digital signal is set to a value which is twice as high as the sampling rate of the chrominance signal.
In the above conventional example, however, since the luminance signal and the chrominance signal are independently processed in parallel, for example, in a case of performing a movement compensating operation, in order to balance the contents of the video images between the luminance signal and the chrominance signal, it is necessary to match the movement information (movement vector), in the luminance signal, with that of the chrominance signal.
When the operator tries to communicate the movement information between the luminance signal and the chrominance signal for this purpose, there are drawbacks such that a scale of hardware to realize such a process is large and the processing operation is also complicated and the like.
Further, when the luminance signal and the chrominance signal are transmitted, if an uncorrectable error occurs, its correcting operation is complicated.
Hitherto, a band compression encoding in which a movement image signal is transmitted at a low bit rate is indispensable to effectively use a transmission path and to reduce the communication costs. Therefore, various kinds of band compressing methods have been examined. Among them, a movement compensation encoding method for encoding in consideration of the movement of an image is promising.
In a conventional apparatus for encoding by performing the movement compensation, however, since the luminance signal and the chrominance signal are independently processed by different circuits, there are the following problems: (1) a circuit scale is large; (2) it takes a long calculating time as a whole; and (3) the costs are high.